Merkel, Balkan leaders to discuss migrants crisis

German Chancellor Angela Merkel and western Balkan leaders are set to gather in Vienna in a bid to find a coherent approach to tackling the biggest migration crisis to hit Europe since World War II.

The meeting on Thursday (local time) comes a day after Merkel vowed zero tolerance for "vile" anti-migrant violence and as criticism grows against the European Union for failing to co-ordinate a solution.

With the situation spiralling further on Wednesday, rescuers found 55 more corpses on stricken boats in the Mediterranean, adding to a toll of more than 2300 people who have drowned while attempting the perilous crossing since the beginning of 2015.

Police fired tear gas in chaotic scenes at a Hungarian border town and Budapest considered deploying troops to stem a record influx of asylum seekers.

Alarmed by the worsening dilemma, UN chief Ban Ki-moon has urged countries "in Europe and elsewhere to prove their compassion and do much more to bring an end to the crisis".

Hamstrung by a lack of a coherent European response, governments have undertaken at times contradictory approaches to the problem.

Hungary is building a vast razor-wire barrier to keep migrants out, while Czech Deputy Prime Minister Andrej Babis has called for the visa-free Schengen zone to be closed with the help of NATO troops.

Meanwhile Germany, which is preparing to receive a record 800,000 asylum-seekers this year, has confirmed it has eased the asylum application procedure for Syrians fleeing the country's brutal civil war, a decision praised by US President Barack Obama in a phone call with Merkel on Wednesday, according to a White House statement.

But Berlin's largesse has not been welcomed by everyone at home, particularly in the east where a spate of attacks has targeted refugee centres.

On her visit to a migrant shelter in the eastern town of Heidenau on Wednesday, Merkel was greeted by about 200 protesters, some booing and shouting "traitor, traitor" and "we are the mob" as she arrived.

But the German leader vowed: "There will be no tolerance of those who question the dignity of other people."

She added that the more people who carry this message, "the stronger we will be and the better we will be able to address this task" of caring for refugees.

Public opinion was largely behind her, with 60 per cent of Germans polled by public broadcaster ZDF saying that Europe's biggest economy was capable of hosting the asylum-seekers.

At least 55 dead bodies were discovered Wednesday on three overcrowded migrant boats in the Mediterranean, according to the Italian coastguard, on a day that saw some 3000 others rescued at sea.

Almost all of the victims were found in the hold of a boat found drifting off the Libyan coast by a Swedish vessel. Media reports said they had choked to death on gas fumes.

The number of people who have died making the crossing in 2015 already exceeds the death toll for the whole of 2014, according to the International Organisation for Migration.

In Hungary, another country overwhelmed by record numbers arriving, there were ugly scenes in the border town of Roszke as police fired tear gas at people who were trying to leave a refugee processing centre after refusing to be fingerprinted.

Hungarian MPs will vote next week on whether to send troops to stem the influx, as more than 2500 people crossed into the EU country from its southern frontier with Serbia, days before the completion of the razor-wire fence.